Expansible plunger for free piston pumping apparatus



Sept. l, i956 S. E. EKLUND EXPANSIBLE PLUNGER FOR FREE PISTON PUMPING APPARATUS Filed Jan. 5, 1955 2 sheets-sheet '1 Sept. 11, 1956 s, E, EKLUND 2,762,310

EXPANSIBLE PLUNGER FOR FREE PISTON PUMPING APPARATUS Filed Jan. 5, 1955 2 Sheets-Sheet 2 S70/VE E, ',ZZ//VD INVENTOR.

.2570. G. 25 57 BY r 1 1951, and entitled Expansible Plunger for C' EXPANSIBLE PLUNGER vFOR PISTON PUMPNG APPARATUS Stone E. Eklund, Torrance, Calif., assignor to The-National Supply Company, Pittsburgh, Pa., a corporation of Pennsylvania Application January 5,1953, Serial No. 329,651

10 Claims. (Cl. 103-52) This invention relates to apparatus of the type used in lifting well uid by means kof a pneumatically driven plunger which travels substantially the full length of an Yeduction tube. Apparatus of this general type is disclosed in the Fletcher Patent 1,846,000 dated February v16, 1932. Certain improvements in the plunger construction are shown in the copending. application of Donald G.- Knox, Serial No. 213,886, filed March 5, Plunger Lifts, now Patent No. 2,684,633.

The eduction tube in which the plunger travels is composed of sections of pipe joined end to end by threaded couplings. It is therefore essential that the plunger construction be such that it will pass freely through a joint between pipe sections and not foul or hang up at the joints. However in order to minimize slippage and consequent loss of well fluid, the plunger must maintain a seal with the inside surface of the sectional well tubing. The present invention meets these conicting requirements in an admirable fashion.

It is accordingly the principal object of thisV invention to provide a novel form of expansible plunger which will provide an effective seal within the eduction .tube and which will not foul or hang up when passing a joint between sections of the eduction tube.

Another object is to provide an expansible plunger of this type employing a plurality of intertting duplicate sealing elements which are spring loaded to move radially outwardly toward sealing position.

A more particular object is to provide an expansible plunger of this type in which the sealing elements are each provided with a relatively narrow stem and a relatively wide head, the head having an external surface shaped to conform to the inner surface `of the eduction tube.

Other and more particular objects and advantages will appear hereinafter.

In the drawings:

Figure 1 is a side elevation showing a plunger embodying my invention.

Figure 2 is a longitudinal sectional View of the upper portion of the plunger, shown on an enlarged scale.

Figure 3 is a sectional View showing the lower portion of the plunger and showing the valve in open position.

Figure 4 is a transverse sectional View taken substantially on the lines 4-4 as shown in Figure 2.

Figure 5 is a transverse sectional view taken substantially on the lines 5-5 as shown in Figure 2.

Figure 6 is a transverse sectional view taken substantially on the 1in-es 6 6 as shown in Figure 2.

Figure 7 is a perspective view showing the back side of one of the sealing elements.

Figure 8 is a perspective view showing the front side thereof.

Referring to the drawing, the plunger 10 includes a body 11 having a central axial passage 12 extending therethrough. The upper portion of the body is provided with an external cylindrical surface 13. The lower end of the body is externally threaded at 14 to receive'the internal threads 15 of the extension 16. A downwardly facing valveseat 17 is provided on this extension :and the conical surface' 18 of the head 1 9` on'the poppet 5` valve 20 is adapted to close against this seat V17 to form la. seal. fA bushing 21 is connected tothe lower end of the extension 16 by threads 22 and is vprovdedwith a cylindrical bore 23 which receives the'valve stem 24 in sliding relationship. The lower end 25 of the valve 10 stenr 24 projects downwardly from `the lower end of the bushing 21. VA plurality of lateral ports 26 are provided in the extension 16 andthese lateral ports communicate with thevcentral opening 12 in the body 11 when the valve is in open position, as shownin Fig- 15 ure 3.

In accordance with my invention, radially `expansible sealing elements'27 are mounted on the body 11 tofform a seal with the interior ofthe eduction tube, not shown. -As shown in Figures 7 and 8, each ofv these sealing ele- 20 ments 27 is provided with a narrow axial stem 28 integrally connected with a wide head 29. A portion 30 Mof kthe outer surface of the head comprises part yof a cylindrical surface while another portion 31 of the outer surface ofthe head comprises part of a conicall surcface. 'The two surfaces merge along the line 32. 1A `curved surface 33 interrupts the conical surface 31- and .terminates at one end along the shoulder 34.` The re- -maining portion of theA curved surface' 33 dies f out -where itintersectsxthe.conical surface 31.

-The purpose of the surface 33 is to. provide a cutting edge alongrtheV shoulder 34 for scraping parain or other Aforeignmatter from thewall of the eduction tube.

The sealing elements 27 are preferably mountedwin .twoiorimoredistinct groups on the plunger 10. -The 35 grstgrouppas shown in the drawings, is positioned above the collar :35 and the second; group is positioned below -the co1lar '35. The body 11 is provided with` av rst eX- ;ternalcylindrical.surface 36 which extends fromy the an- :nularrshoulder 37to the `annular shoulder 38. The body 40 1l` isvgalso yprovided with a second external cylindrical surface 39 whichwextends'from'the annular shoulder/"46 .toftheannular :shoulder 41. The collar Y35 is of split construction and is Vmountedv on the body `at a location :betweenthe shoulders38 and 41, beingfxed in position bymeans--of threaded fasteningsAZ. 'The collar'35 is provided with ,anmupwardly extending annular `rimf- 43 Yand adownwardly extendingannular skirt 44. Similarly the body 11 is provided with a downwardly extending 4skirt45 andrthe extensionV 16 is provided with an upwardly extending rimf46. Annular recesses 47,. 48,'49

-and` 50, are thus defined vbetween the skirt 45v and surface 36, the rim 43 and the surface 36,'the skirt 44 and the surface 39, and the rim 46 and the surface 39, respectively. .-Each sealingV element 27 vis provided with a narrow. :tab -51 Fat theend of the stem 28and a wide ltab 52 atthe Vendl of the head 29. These tabs 51 and 52 arev positionedwithin the annular recesses just described.

Resilient meansareprovided for biasing each of the sealingelements to move radially. outwardly. As shown in .the drawings, this means comprisesa compression spring 53 mounted within a recess 54A provided inthe back side-of each .of thesealing elements 27. Each recess 54` is located near lthe projecting end of the stern 28. EachspringSScontacts one of -.the surfaces 36er 39 on the bodyl 11. Outward movement of the-'sealing elements 27..under `theforce of the springs is arrestedv by engagement of thetabs 51 and 52 with the skirts 44 and 45 and rims 43 and 46.

Each, group of sealing elements comprises ar plurality of upwardly Yfacing elements` and an equal-numberof downwardlyV facing elements. The elements are mounted in interitting nested relationship,Y as best shown in Figures 5 and 6. The upwardly facing stem 28 on alternate sealing elements is positioned between upwardly facing heads 29 on adjacent elements. Similarly, downwardly directed stems 28 are positioned between downwardly extending heads 29. In the particular embodiment of my invention shown in the drawings, each group comprises eight sealing elements, four with upwardly directed stems and four with downwardly directed stems. It will be understood that a larger or smaller number of sealing elements may be employed in each group but it is necessary that the same number of upwardly facing stems be provided as downwardly facing stems.

The side edges 56 of each head 29 overlap a ,portion of each stem 28 and the surfaces 57 and 57a on the back side of each head 29 are shaped to rest against the axially extending curved surfaces 5S on the stems 28. These surfaces 57, 57a, and 53 are held in engagement by the action of the springs 53.

The sealing elements 27 are mounted in nested overlapping relationship on the body 11 and are held in position against displacement by means of the split collar 35. The assembled plunger is then ready for operation within an eduction tube. The plunger drops by gravity down through the interior of the eduction tube while the valve 20 remains in open position, as shown in Figure 3. A ring magnet 59 may be mounted within the extension 16 to act upon the valve head 19 in order to insure that the valve remains open during the descent of the plunger. The upper end of the magnet 59 engages an annular shoulder 60 provided on the extension 16. A resilient ring element 61, which may be formed of synthetic rubber, holds the magnet 59 against the shoulder 60. Downward travel of the valve is limited by engagement of the stop pin 62 with the shoulder 63 on the stern 24, and by this means the valve head is prevented from striking a hammer blow upon the magnet S9.

When the plunger 10 reaches the lower end of the eduction tube, the lower end 2S of the valve stem strikes a bumper device, not shown, which closes the valve and brings the conical surface 18 into engagement with the seat 17. Gas pressure below the plunger then raises it to the surface and brings up a load of well liuid above the plunger. The valve 20 remains closed while the plunger travels upward through the eduction tube.

The plunger and the sealing elements 27 thereof pass the joints between sections of the eduction tube without interference and without any tendency to hang up at the joints. The self-expanding action of the sealing units enables the plunger to maintain sealing contact with the interior of the eduction tube even though the latter varies considerably in internal dimensions.

Having fully described my invention, it is to be understood that I do not wish to be limited to the details herein set forth but my invention is of the full scope of the appended claims.

I claim:

1. In an expansible plunger, the combination of: a body, a radially expansible sealing assembly on the body including a plurality of nested sealing elements having portions thereof shaped to engage the inner surface of an eduction tube, each of the sealing elements comprising a head and an axially extending stem, certain of the sealing elements being mounted with their stems projecting in one direction and the remaining sealing elements being mounted with their stems projecting in the opposite direction, each of the heads having side edges overlying a portion of the stem of another of the sealing elements, resilient means acting to move said sealing elements radially outwardly, and means on the body for limiting movement thereof under action of said resilient means.

2. In an expansible plunger, the combination of: a body, a radially expansible sealing assembly on the body including eight nested sealing elements having portions thereof shaped to engage the inner surface of an eduction tube, each of the sealing elements comprising a head and an axially extending stem, four of the sealing elements being mounted with their stems projecting in one direction and the remaining four sealing elements being mounted with their stems projecting in the opposite direction, each of the heads having side edges overlying a portion of the stem of another of the sealing elements, resilient means acting to move said sealing elements radially outwardly, and means on the body for limiting movement thereof under action of said resilient means.

3. In an expansible plunger, the combination of: a body, a radially expansible sealing assembly on the body including a plurality of nested sealing elements encircling the body and having portions thereof shaped to engage the inner surface of an eduction tube, each of the sealing elements comprising a head and an axially extending stem, one-half of the number of sealing elements being mounted with their stems projecting in one direction and the remaining sealing elements being mounted with their stems projecting in the opposite direction, each of the heads having side edges overlying a portion of the stem of another of the sealing elements, resilient means interposed between the body and said sealing elements and acting to move said sealing elements radially outwardly, and means on the body engageable with the opposed ends of said sealing elements for limiting movement thereof under action of said resilient means.

4. In an expansible plunger, the combination of: a body, a radially expansible sealing assembly on the body including a plurality of nested sealing elements, each of the sealing elements comprising a transversely curved arcuate head, at least a portion of the outer surface of the head being shaped to engage the inner surface of an eduction tube, an axially extending stem integrally connected to the head, the head being wider than the stem, the head and stem each having side edges provided with axially extending contact surfaces, one-half of the number of sealing elements being mounted with their stems projecting in one direction and the remaining sealing elements being mounted with their stems projecting in the opposite direction, each of said contact surfaces on the heads overlying and engaging one of the contact surfaces on one of the stems, resilient means acting to move said sealing elements radially outwardly, and means on the body for limiting movement thereof under action of said resilient means.

5. A sealing element for an expansible plunger, comprising in combination: a head, at least a portion of the outer surface of the head being shaped to engage the inner ysurface of an eduction tube, an axially extending stem integrally connected to the head, the head being wider than the stem, the head and stem each having side edges provided with axially extending contact surfaces, the said contact surfaces being positioned so that they engage similar surfaces on a duplicate sealing element reversed end for end and placed adjacent thereto.

6. A sealing element for an expansible plunger, comprising in combination: a head, at least a portion of the outer surface of the head being shaped to engage the inner surface of an eduction tube, an axially extending stem integrally connected to the head, the head being wider than the stem, the head and stem each having side edges provided with axially extending contact surfaces, the said contact surfaces being positioned so that they engage similar surfaces on a duplicate sealing element reversed end for end and placed adjacent thereto, and a spring receiving recess provided on the back side of the stem near the projecting end thereof.

7. A sealing element for an expansible plunger, comprising in combination: a transversely curved arcuate head, at least a portion of the outer surface of the head being shaped to engage the inner surface of an eduction tube, an axially extending stem integrally connected to the head, the head being wider than the stern, the head and stem each having side edges provided with axially extending contact surfaces, the position of said contact surfaces being such that a head surface and a stem surface engage a stem surface and a head surface, respectively, on a duplicate sealing element reversed end for end and placed adjacent thereto.

8. A sealing element for an expansible plunger, comprising in combination: a transversely curved arcuate head, at least a portion of the outer surface of the head being shaped to engage the inner surface of an eduction tube, an axially extending stem integrally connected to the head, the head being wider than the stem, the head and stem each having side edges provided with axially extending contact surfaces, the position of said contact surfaces being such that a head surface and a stem surface engage a stem surface and a head surface, respectively, on a duplicate sealing element reversed end for end and placed adjacent thereto, and a spring receiving recess provided on the back side of the stem near the projecting end thereof.

9. A sealing element for an expansible plunger, cornprising in combination: a transversely curved arcuate head, a first portion of the outer surface of the head being shaped as a portion of a cone and a second portion being -shaped as a portion of a cylinder, said portions merging together, an axially extending stem integrally connected to the head adjacent said second portion thereof,

the head being wider than the stem, the head and stem each having side edges provided with axially extending contact surfaces, the position of said contact surfaces being such that they engage similar surfaces on a duplicate sealing element reversed end for end and placed adjacent thereto.

10. A sealing element for an expansible plunger, comprising in combination: a transversely curved arcuate head, a first portion of the outer surface of the head being shaped as a portion of a cone and a second portion being shaped as a portion of a cylinder, a third portion of the head interrupting the rst portion and terminating in an arcuate shoulder adjacent said first portion, an axially extending stem integrally connected to the head adjacent said second portion thereof, the head being wider than the stern, the head and stem each having side edges provided with axially extending contact surfaces, the position of said contact surfaces being such that they engage similar surfaces on a duplicate sealing element reversed end for end and placed adjacent thereto.

References Cited in the le of this patent UNITED STATES PATENTS 

